Study the graph given below related with menstrual cycle in females:
a. Identify ovarian hormones X and Y mentioned in the graph and specify their source.

Corelate and describe the uterine events that take place according to the ovarian hormone levels X and Y mentioned in the graph on -
i. 6 – 15 days
ii. 16 – 25 days
iii. 26 – 28 days (when ovum is not fertilized)

Explanation

a. X- Estrogen secreted by growing follicles,
Y – Progesterone secreted by corpus luteum
b. Uterine events that take place according to the ovarian hormone levels X and Y on -
i. 6 – 15 days: Endometrium of the uterus regenerates by proliferation under the influence of estrogen.
ii. 16 – 25 days: Under the influence of Progesterone the endometrium of the uterus is maintained for implantation of fertilised ovum and other events of pregnancy.
iii. 26 – 28 days (when ovum is not fertilized): in the absence of fertilisation, corpus luteumdegenerates which causes disintegration of endometrium leading to menstruation, marking a new cycle.